Wire stringing device



p 1964 J. M. MOKEE 3,148,033

WIRE STRINGING DEVICE Filed June 14, 1962 g) r Inn-Inna unman-wt...

INVENTOR FlG. 2 BY JOHN M. MQKEE ,ZY f ATTORNEYS United States Patent 3,148,033 WIRE STRTNGING DEVICE John M. McKee, Armonlr, N.Y., assignor to United Nuclear Corporation, ite Plains, N.Y., a corporation of Delaware Filed dune 14, 1962, Ser. No. 203,142 ill Claims. (Cl. 23-254) This invention relates generally to gas testing devices and more specifically to a filament stringing device used in conjunction with gas testing devices of the kind that expose heated metallic filaments to an atmosphere of the gas to be tested to determine the presence and amounts of reactive constituents in the gas.

Methods are known by which the amounts of impurities or reactive components present in a specimen of gas can be determined by exposing a heated filament to a sample of the gas to be analyzed. In known devices for use in the practice of these methods filaments of reactive metals are strung between electrodes situated in an enclosure containing the test gas. The electrodes are connected to a source of electrical power by which the filament bridging the electrodes is heated to hasten the reaction between the impurities in the gas and the metallic filament. The length of time a heated filament of given size remains intact may be emp rically related to the kind and amount of reactive components of the gas that is being tested.

The empiric nature of the testing makes it desirous to burn several filaments in rapid succession in order to get accurate results. My wire stringing device has particular value when it is used to string filaments in a gaseous environment that has to be closely monitored. For example, if one were working with a material similar to sodium in an inert gas environment, it would be extremely desirable to determine quickly and accurately the kinds and amounts of impurities present in the environment as the work with the sodium progressed. Certainly, during the course of working with the sodium, it would be necessary to string a number of filaments as they would burn out upon reaction with the impurities. In most of the prior art devices, in order to string a new filament it was necessary to either destroy the integrity of the environment, in which case it would be necessary to re-establish the original conditions or to tediously manipulate the extremely small diameter filaments through a glove port. In both instances, the stringing operation was laborious and ineificient.

I have invented a wire stringing device which obviates the difiiculties inherent in the accurate testing of gas samples by providing means whereby new filaments from a continuous supply can be strung between the electrodes without disturbing the conditions of the gas Within the enclosure.

According to my invention a stringing device used as part of a testing device for determining the reactive components of a mixture of confined gases comprises a frame pivotably mounted within the enclosure. At least two filament supporting means are mounted on the frame at locations spaced from the axis about which the frame is pivotably mounted and there is provided a means for pivoting the frame about its axis. There are gripping means located on each of the supporting means for releasably securing the filaments to the supporting Edd-33 ice means. Cam means are associated with the sectu'ing means for actuating the securing means at predetermined positions of the pivotable frame and a filament guide means is constructed and arranged such that it receives the filament from the source and delivers it into the path in which the filament securing means move about the pivot axis. Further, there is means for connecting the filament strung between the supporting means in circuit with a source of electrical power.

The novel combination of elements according to my invention produces advantages which eliminate the difficulties encountered in testing gases with the prior art devices. In regard to the stringing device, an important feature is the cooperative relationship between the parts of the electrodes and the cam. The uniquely constructed electrodes functioning as both electrical conducting and filament gripping means are supported in a pivotal frame member. At predetermined angular positions of the frame member, an extended portion of a filament supporting electrode comes into contact with the cam. Upon contact with the cam, the filament gripping means located on the filament supported member is positioned so that an end portion of a burned filament is released. At another predetermined position of the frame, an extended portion of the filament support members drops free of the cam; at this point the filament securing means on the filament support member is positioned so that it firmly grips an end of the filament that is being extended from the source.

It is this co -operative relationship between the multipurpose electrodes supported in a frame pivoted from a position remote from the gas enclosure and the cam that results in a mechanical combination that obviates many of the difficulties inherent in the previous devices used to test gas.

In a preferred embodiment of my invention the unique structure of the electrodes enables them to achieve the filament supporting, securing and electrical conducting functions. They are made in two parts; a lower gripping member having a first face portion is fixedly attached to the pivotable frame while an upper gripping member having a second face portion slides into and out of contact with the fixedly attached first face portion. The position of the second face portion with respect to the first portion determines whether or not the filament is gripped or released by the electrode. This position is determined by slidable displacement of an integral rod extending from the second face portion. This rod acts like a cam follower when it moves across the surface of the cam. At a predetermined position of the pivotable frame and therefore, the electrodes relative to the cam, the face portions will either be in a filament contacting or gripping position or a non-contacting or filament releasing position.

In this preferred embodiment there are spring actuated electrical contact members which connect the filament bridged between the electrodes to an outside power source when the frame is pivoted to a filament testing position. When a filament is broken during the testing of a gas sample and the frame pivoted in order to string a new filament, the contacts are positioned so that there is no longer an electrical connection between the filament and the outside source of power. This feature of my device prevents a possible short circuit developing between the masses broken filament and other parts of the Wire stringing device.

Other features and advantages of the invention will become apparent from the following detailed description of a preferred embodiment of the invention. In this description reference is made to the accompanying drawing in which:

FIG. 1 is an elevation view of the testing apparatus, partly broken away, showing the arrangement of the major components of the wire stringing device.

FIG. 2 is a cross-sectional view taken along lines 22 of FIG. 1.

The major components of the wire stringing device, designated by 10, are mounted generally along the longitudinal centerline of an electrically non-conducting support plate 12. A shield 14 encompassing the wire stringing components is fixed to the support plate 12 to form a housing for the wire stringing device in order to protect the filament from wind and dust. For typical testing purposes the device is placed inside of a larger air tight container or enclosure with the column 39 extending through a rotary seal. The column is fixed to a handle 3 on the outside of the air tight container so that the wire stringing device can be operated without disturbing the gas condi tions. Many variations of remotely actuating the device can be envisioned. For example, glove ports can be provided in the air tight container or remotely controlled electrical, mechanical, and pneumatic actuators can be used. The shield is usually provided with two large holes 16 so that the gas conditions inside the shield are similar to the conditions existing throughout the other portions of the air tight container. The placement of the stringing device in the gas to be tested eliminates the need for a gas sampling line so that continuous recirculation systems are eliminated.

The components of the wire stringing device comprise a source of metallic filament I? wrapped around the periphery of a spool pivotably mounted on one side of the base plate 12. The filaments are generally made of metals such as titanium or tantalum and are usually of small diameters for best test results; typically wires having diameters of the order of three-thousandths (0.003) of an inch are used. The filament 18 is led from the periphery of the spool 20 through a guide means 22 mounted on the plate 12 adjacent to the spool 20 and ultimately bridged across a pair of electrodes designated generally as 24 and 26. The electrodes are mounted on a frame member 28 pivotable about a column 3-0 which is fixed to the plate 12. The electrodes 24 and 26 are spaced equidistant from the column 30.

A cam 36 is fixed to the base plate and lies generally abreast of the column between the column 30 and the filament guide means 22. Leaf springs 38 secured to support blocks 40 located on both sides of the centerline of the plate 12 extend from a position generally abreast the filament guide means into contacting relationship with the electrodes 24 and 2 6. One of the leaf springs is detented to provide a stop point for the rotating electrodes. The characteristics of the similarly constructed electrodes 24 and 2d are depicted in FIG. 2, a description of the electrodes continuing with reference to the electrode 26 which is typical.

The lower gripping member of the electrode 26 is comprised of a first face portion 42 which is generally convex and for simplicity it is preferably a segment of a sphere. The gripping member also comprises a supporting stem 44 which is assembled by means of a press fit into a slot provided in the frame. The face portion 42 and the stem 44 are provided with an aperture 46 extending through both portions. An insulating bushing 48 is inserted in the slot located in the frame 28 between the cylindrical stem and the frame. A suitable bushing material is glassbonded mica. The upper gripping member of the electrode 26 is comprised of a second face portion 50 shaped similarly to the first face portion 42, and an integral rod member 52. The rod member 52 extends perpendicularly from the second face portion through the aperture 46 in the stem and face portions of the lower half of the electrode. The integral rod member 52 is slidable within the aperture 46 out is biased by a spring 54 attached to and extending along the length of the rod so that the first and second face portions of the electrode are normally in contacting relationship.

The gripping members are designed so that their opposed convex surfaces provide both a guiding channel for the filament and a means for gripping the strung filament. The integral rod 52 of the upper gripping member 50 terminates at a point considerably below the frame where it is intermittently contacted by the leaf springs 38. A conducting member 56 extends from the underside of the leaf springs 38, to a suitable source of external power which is not shown in the drawings. This external source can take many forms depending on the type of power that is available or most desirable to heat the filament. Advantageously the power for heating the filament is supplied from a constant current source. Supplying electricity of constant current to the filament has a number of advantages; namely, it virtually eliminates the effect of the contact resistance at the clamping electrodes thereby reducing another variable which alfects the filament behavior. Further, constant current produces a constantly rising filament temperature as the filament resistance increases due to the pick-up of impurities. This increases the diffusion rate of the impurities from the surface into the metal and accelerates the failure of the filament which is a desirable feature. Furthermore, a constant current supply prevents saturation of the metal surface with impurities and avoids loss of quantitative response to gas purity.

In addition to periodically contacting the spring 33 the integral rod 52 can contact the semi-circular cam 36 located between the guide means 22 and the pivotable frame member.

The components of the wire stringing device used to conduct tests of gas samples having been described, it is desirable to explain the procedure that is followed in stringing a filament after a previous one has broken.

When a filament breaks, the parts are left hanging from the electrodes 24 and 26, the portion of the filament gripped by the electrode 26 being part of the supply of filament extending from the source 20. To string a new filment between the electrodes, the operator merely turns the handle 34, causing rotation of the electrode carrying frame and further extension of the filament from the source of supply. When the frame is rotated in the direction of the arrow approximately 5 from the starting point, as shown in FIG. 1, the rod member 52 which is integral with the upper gripping member 50 of the electrode 26 contacts the cam 36 which underlies a portion of the path followed by the electrodes as they are rotated. At first contact of the rod, acting now like a cam follower, and the cam, the rod is caused to slide outwardly with respect to the frame 28. Hence, the first and second face portions of the upper and lower gripping member separate causing a portion of the broken filament to drop free of the electrode. When the frame is rotated approximately from the starting point, the electrode 26 with its now separated face portions comes into contact with a portion of the filament 18 being extended from the spool 20. The convex surfaces of the face portions guide the filament into contact with rod 52, and as the frame continues to rotate, the filament is wrapped around rod 52. When the frame has rotated approximately from the starting point, rod 52 drops off the end of cam Bio-allowing spring 54 to bias the second face portion of the electrode into contact with the first face portion, thereby gripping the filament being extended from spool 20. The filament is now bridged across the frame and all that remains is to rotate the frame through approximately an additional 10 so that the electrode 24, upon contact with the detent, is now positioned where the electrode 26 was at the start of the stringing operation. At this position, the testing position, the electrodes again contact the leaf springs 38 completing the electrical circuit to the external power source.

My unique wire stringing device allows a new fila ment to be strung with every 180 turn of the pivotable frame, thus permitting a quick return to the testing of the gas.

My invention is not limited to the details of the pre ferred embodiment described above. The full scope of my invention is defined in the following claims.

I claim:

1. For use with a testing device for determining the presence and amounts of reactive components in a mix ture of gases confined to an enclosure, a filament string ing device positioned in the enclosure comprising:

(a) a source of filament,

(b) a pivotably mounted frame,

(0) at lease two filament supporting means mounted on said frame at positions spaced from the pivot axis of said frame, and means for pivoting said frame,

(d) gripping means on each of said supporting means for releasably securing the filament to said supporting means simultaneously at said spaced portions,

(e) cam means positioned along the path of move ment of said supporting means for successively re leasing each of said gripping and securing means at pre-determined positions of said frame,

(1) filament guide means constructed and arranged to receive filament from said source and deliver it into the path in which said filament gripping means move about said pivot axis,

(g) and means for connecting filament strung between said supporting means in circuit With a source of electrical power when said frame is positioned at predetermined positions.

2. For use with a testing device for determining the presence and amounts of reactive components in a mixture of gases confined in an enclosure, a filament stringing device positioned in the enclosure comprising:

(a) a source of filament,

(b) a pivotably mounted frame,

(c) at least two filaments supporting electrodes mounted on said frame at positions spaced from the pivot axis of said frame and means for pivoting said frame,

(d) gripping means on each of said supporting electrodes for releasably securing the filament to said electrodes simultaneously at said spaced portions,

(e) cam means disposed along the path of movement of said supporting-electrodes for successively releasing each of said gripping means at predetermined positions of said frame,

(f) filament guide means constructed and arranged to receive filament and deliver it into the path in which said filament gripping means move about said pivot axis,

g) and means for connecting filament strung between said electrode supporting means in circuit with a source of electrical power.

3. For use With a testing device for determining the presence and amounts of reactive components in a mixture of gases confined in an enclosure, a filament stringing device positioned in the enclosure comprising:

(a) a source of filament,

(b) a pivotably mounted frame,

(0) at least two filament supporting electrodes mounted on said frame at positions spaced from the pivot axis of said frame and means for pivoting said frame,

(d) each of said electrodes having filament gripping means thereon for releasably securing the filament simultaneously to each of said electrodes, said gripping means comprising, a first face portion fixedly attached to said frame and a second face portion mounted in sliding relation with said first portion,

(e) cam means disposed along the path of movement of said electrodes for engaging said electrodes to slide the second face portion of said filament gripping means out of contact with said filament at predetermined angular positions of said frame,

(f) filament guide means constructed and arranged to receive filament and deliver it into the path in which said filament gripping means move about said pivot axis,

(g) and means for connecting filament strung between said supporting means in circuit with a source of electrical power.

4. For use with a testing device for determining the presence and amounts of reactive components in a mixture of gases confined in an enclosure, a filament stringing device positioned in the enclosure comprising:

(a) a source of filament,

(b) a pivotably mounted frame,

(c) filament supporting electrodes mounted on said frame at positions equidistant from the pivot axis of said frame and means for pivoting said frame,

(d) each of said electrodes having a filament gripping means therein for releasably securing the filament simultaneously to each of said electrodes, said gripping means comprising a first face portion fixedly attached to said frame, a second face portion mounted in sliding relation with said first portion and a rod member integral with and extending away from said second face portion,

(a) cam means positioned along the path of movement of said rod members whereby at pro-determined angular positions of said frame, a rod member contacts said cam causing separation of said first and second electrode face portions from filament gripping position,

(f) filament guide means, positioned between said source and said frame, and arranged to receive filament and deliver it into the path in which said filament securing means move about said pivot axis,

(g) and means for connecting filament strung between said supporting means in circuit with a source of electrical power.

5. For use with a testing device for determining the presence and amounts of reactive components in a mixture of gases confined in an enclosure, a filament stringing device positioned in the enclosure, comprising:

(a) a source of filament,

(b) a pivotably mounted frame,

(0) filament supporting electrodes mounted on said frame at positions equally spaced from said pivot axis and means for pivoting said frame,

(d) each of said electrodes having a filament gripping means therein for securing the filament simultaneously to each of said electrodes, said gripping means comprising a first face portion fixedly attached to said frame, a second face portion mounted in sliding relation with said first portion, said second face portion being biased into contact with said first face portion at first pro-determined angular positions of said frame, and a rod member integral with and extending away from said second face portion,

(e) cam means positioned along the path of movement of said rod members whereby at second pre-determined angular positions of said frame, a rod member contacts said cam thereby separating said electrode faces from a filament gripping position,

(1) filament guide means, positioned between said source and said frame, and arranged to receive filament and deliver it into the path in which said filament gripping means move about said pivot axis,

(g) and means for connecting filament strung between said supporting means in circuit with a source of electrical power,

6. A testing device for determining the presence and amounts of reactive components in a mixture of gases confined in an enclosure by successively burning filaments mounted between electrodes in the enclosure comprising:

(a) a housing positioned within said enclosure with the interior thereof in limited communication with the interior of said enclosure,

(1)) a filament stringing device positioned within said housing for providing a succession of filaments bridged across said electrodes, said stringing device comprising:

(1) a source of filament,

(2) a pivotably mounted frame,

(3) at least two filament supporting means mounted on said frame at positions spaced from said pivot axis and means located externally of said enclosure for pivoting said frame,

(4)gripping means on each of said supporting means for simultaneously releasably securing the filament to each of said supporting means,

(5) cam means positioned along the path of movement of said filament securing means for releasing said gripping and securing means at pro-determined position of said frame,

(6) filament guide means constructed and arranged to receive filament and deliver it into the path in which said filament gripping means move about said pivot axis and (7) means for connecting filament strung between said supporting means in circuit with a source of electrical power.

7. For use with a testing device for determining the kinds and degree of impurities present in a gas by successively burning reactive metal filaments strung between electrodes mounted in the enclosure comprising:

(a) a housing positioned within said enclosure with the interior thereof in limited communication with the interior of said enclosure,

(12) a filament stringing device mounted Within said housing for providing a succession of filaments bridged across said electrodes comprising:

(1) a source of filament,

(2) a pivotably mounted frame,

(3) at least two filament supporting means mounted on said frame at positions spaced from said pivot axis and means located externally of said enclosure for pivoting said frame,

(4) each of said electrodes having a filament gripping means therein for simultaneously releasably securing the filament to each of said electrodes, said gripping means comprising a first face portion fixedly attached to and insulated from said pivotable frame, a second face portion mounted in sliding relation with said first portion, said second face portion being normally biased into contact with said first face portion, and a rod member integral with and extending away from said second face portion,

(5 cam means positioned along the path of move ment of said rod members for engaging said rod at predetermined angular positions of said frame to separate the associated electrode faces from filament gripping position,

(6) filament guide means, positioned between said source and said frame, and arranged to receive filament and deliver it into the path in which said filament gripping means move about said pivot axis,

(7) and means for connecting filament strung between said supporting means in circuit with a source of electrical power.

8. For use in connection with the electrodes positioned on a pivotable frame portion of a stringing device used for bridging successive filaments across the electrodes for burning with the reactive components in a gas filled atmosphere, a pair of cam-actuated filament gripping means each comprising:

(a) a first face portion fixedly attached to said pivot- 5 able frame,

([1) a second face portion sildably mounted with respect to said first face portion,

(0) a rod member integral with and extending away from said second face portion for engaging and disengaging said cam along the path of movement of said rod to thereby slide the electrode face portions into filament gripping and releasing positions at predetermined angular positions of said pivotable frame.

9. For use with a testing device for determining the 15 presence and amounts of reactive components in a mixture of gases confined in an enclosure, a filament stringing device adapted to be positioned in the enclosure comprising:

(a) a support for holding a source of filament,

(b) a first filament gripping means for releasably gripping said filament at a first point along a length of the filament extending way from said source,

(c) a second filament gripping means for simultaneously releasably gripping said filament at a second point along said length of filament spaced from said first point in a direction extending away from said source,

(:13) means for moving said second filament gripping means relative to said length of filament along a predetermined path and into gripping engagement with said length of filament at a third point spaced from said first point in a direction toward said source,

(6) means disposed along said path for releasing said second gripping means from gripping engagement with said filament, and

(f) means for connecting filament gripped between said first and second gripping means in circuit with a source of electrical power.

10. A filament stringing device for stringing a length of filament extending from a source of filament between two spaced points comprising:

(a) a support for holding a source of filament,

(b) a pivotally mounted frame,

(0) a first filament gripping means mounted on said frame for gripping said length of filament at a first point,

(d) a second filament gripping means mounted on said frame spaced from said first gripping means for gripping said length of filament at a second point spaced from said first point in a direction extending away from said source,

(e) means normally biasing said first and second gripping means into gripping engagement with said length of filament simultaneously at said first and second points,

(f) means for pivoting said frame about said axis to move said second gripping means through a predetermined path and into gripping engagement with said length of filament at a third point disposed between said source and said first point,

(g) cam means disposed along said path for releasing said second gripping means from gripping engagement with said filament, and

(It) means for connecting said filament gripped between said first and second gripping means in circuit with a source of electrical power.

11. A filament stringing device for stringing a length of filament extending from a source of filament between two points comprising:

(a) a support for holding a source of filament,

(b) a pivotally mounted frame,

(0) a first filament gripping electrode for gripping said length of filament at a first point comprising a first face portion fixed to said frame and a second face portion slidably mounted with respect to said first face portion and having a rod member integral therewith and extending through said first face portion,

(d) a second filament gripping electrode substantially identical to said first electrode mounted on said frame at a position spaced from said first electrode for gripping said length of filament at a second point spaced from said first point in a direction extending away from said source,

(e) means normally biasing said face portions into gripping engagement with said filament simultaneously at said first and second points,

(f) means for pivoting said frame about said axis to move the face portions of said second electrode into gripping engagement with said length of filament 10 at a third point disposed between said source and said first point, and (g) means for connecting said rods in circuit With a source of electrical power at predetermined angular positions of said frame.

References Cited in the file of this patent UNITED STATES PATENTS 10 2,142,251 Nunan Jan. 3, 1939 2,279,231 Gier Apr. 7, 1942 2,321,646 Blodgett June 15, 1943 2,996,086 Neff Aug. 15, 1961 3,009,785 Kaarlela Nov. 21, 1961 

1. FOR USE WITH A TESTING DEVICE FOR DETERMINING THE PRESENCE AND AMOUNTS OF REACTIVE COMPONENTS IN A MIXTURE OF GASES CONFINED TO AN ENCLOSURE, A FILAMENT STRINGING DEVICE POSITIONED IN THE ENCLOSURE COMPRISING (A) A SOURCE OF FILAMENT, (B) A PIVOTABLY MOUNTED FRAME, (C) AT LEAST TWO FILAMENT SUPPORTING MEANS MOUNTED ON SAID FRAME AT POSITIONS SPACED FROM THE PIVOT AXIS OF SAID FRAME, AND MEANS FOR PIVOTING SAID FRAME. (D) GRIPPING MEANS ON EACH OF SAID SUPPORTING MEANS FOR RELEASABLY SECURING THE FILAMENT TO SAID SUPPORTING MEANS SIMULTANEOUSLY AT SAID SPACED PORTIONS, (E) CAM MEANS POSITIONED ALONG THE PATH OF MOVEMENT OF SAID SUPPORTING MEANS FOR SUCCESSIVELY RELEASING EACH OF SAID GRIPPING AND SECURING MEANS AT PRE-DETERMINED POSITIONS OF SAID FRAME, (F) FILAMENT GUIDE MEANS CONSTRUCTED AND ARRANGED TO RECEIVE FILAMENT FROM SAID SOURCE AND DELIVER IT INTO THE PATH IN WHICH SAID FILAMENT GRIPPING MEANS MOVE ABOUT SAID PIVOT AXIS, (G) AND MEANS FOR CONNECTING FILAMENTS STRUNG BETWEEN SAID SUPPORTING MEANS IN CIRCUIT WITH A SOURCE OF ELECTRICAL POWER WHEN FRAME IS POSITIONED AT PREDETERMINED POSITION. 